I. What is Linear Accelerator Radiotherapy?

A linear accelerator is a medical device that uses an electromagnetic field to accelerate electrons to near the speed of light, then generates high-energy X-rays or electron beams to precisely irradiate tumors.

👉 The core objective can be summarized in one sentence: Kill tumors with the maximum dose while minimizing damage to normal tissue.

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II. How Does a Linear Accelerator “Kill” Tumors?

🔬 Mechanism of Action (Simplified Version)

• High-energy rays → Break tumor cell DNA

• Tumor cells:

• Poor DNA repair ability

• Rapid division → More prone to death

• Normal cells:

• Strong repair ability

• Recovery is possible through fractionated irradiation

📌 Therefore, radiotherapy is usually performed in multiple fractionated irradiations.

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III. Which tumors can a linear accelerator treat?

✅ Common Indications

Covering almost 70–80% of cancer patients

Solid Tumors

• Lung Cancer (NSCLC/SCLC)

• Breast Cancer

• Prostate Cancer

• Head and Neck Cancer (Nasopharyngeal Carcinoma, Oropharyngeal Carcinoma)

• Brain Tumors (Gliomas, Metastases)

• Cervical Cancer / Rectal Cancer

• Liver Cancer (in conjunction with precision radiotherapy)

Others

• Bone Metastasis Pain Relief

• Postoperative Adjuvant Radiotherapy

• Radical Treatment for Inoperable Patients

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IV. What are the “Advanced Modes” of Modern Linear Accelerators?

This is the core of the technological gap 👇

1️⃣ IMRT (Intensity Modulated Radiotherapy)

• Different doses at each angle

• Strong tumor-reducing ability

• Protects the spinal cord, optic nerve, etc.

2️⃣ VMAT (Volume Modulated Amplitude Radiotherapy)

• The machine rotates while delivering the radiation

• Short treatment time (2–5 minutes)

• More patient comfort

3️⃣ IGRT (Image-Guided Radiotherapy)

• CT/CBCT calibration before each irradiation

• Error < 1–2 mm

4️⃣ SRS/SBRT (Stereotactic Radiotherapy)

• High dose, fewer sessions

• Suitable for:

• Brain metastases

• Early-stage lung cancer

• Oligometastatic tumors

📌 This type of technology is close to “precision strikes without a scalpel”

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V. A complete linear accelerator treatment process

🧭 Standard procedure

1️⃣ Positioning CT

• Fix the patient’s position (thermoplastic membrane/ 1. Vacuum mat

2. Target delineation

• Tumor area (GTV / CTV / PTV)

• Organs at risk (OAR)

3. Physical therapy planning

• Dosage calculation + optimization

4. Treatment implementation

• 5 times per week

• 4–7 weeks (depending on protocol)

5. Efficacy & side effect monitoring